Placodus

Name meaning:

From Greek plax, plakos — “plate” and odous — “tooth.”

Period of life:

240 million years ago

Period:

Triassic period

Habitat:

Coasts

Taxonomy:

Marine reptiles

Countries:

Silesaurus

Hesperosuchus

Placodus (240 million years ago)

Placodus was a remarkable marine reptile of the Middle Triassic, living about 240 million years ago. Its fossils are found in Central Europe (Germany, France, Poland) as well as in China. The name Placodus means “flat tooth,” referring to its unusually shaped molars.

Placodus had a very distinctive appearance. It was a large reptile, reaching 2–3 meters in length, with a heavy body and a long tail. The vertebrae, ribs, and belly ribs (gastralia) were greatly thickened, and a row of bony knobs ran along the spine. Together these features formed a strong “armor” and added weight that helped the animal stay near the bottom of shallow seas.

Its limbs were short and powerful, more like webbed lizard legs than true flippers. Placodus maneuvered in the water using these limbs and its flattened tail. It was not a fast swimmer but rather a slow-moving bottom-dweller.

The head of Placodus was relatively small but very unusual. At the front of the jaws it had chisel-like teeth used to pry shells and other bottom-dwelling organisms from the seafloor. Deeper in the mouth were broad, flat, pebble-like teeth that crushed hard shells and armor to reach the soft tissue inside. Like many ancient reptiles, Placodus had a pineal opening on top of its skull—a light-sensitive organ that likely helped it detect day–night cycles and regulate biological rhythms.

Although Placodus could probably haul itself onto land, it spent most of its life in coastal marine waters near the bottom. There it moved slowly across soft sediment, searching for shells, brachiopods, marine invertebrates, and possibly algae.

Placodus belonged to the placodonts—a specialized group of Triassic marine reptiles. Some placodonts were relatively lightly armored like Placodus itself, while others had true shells resembling those of turtles. Studying Placodus and its relatives helps scientists understand how early reptiles adapted to marine environments and what evolutionary pathways led to the emergence of various types of marine “armored” animals.

Discussions

No discussions yet

Start the first one!

Start a discussion